Method and communication device for expanding the range of data transmission rates in wireless local area networks

ABSTRACT

A communication device and a method for transmitting data in wireless local area networks is provided. The device and method are deployed in networks in which the data information elements include an element identification part, a length statement part and an information part. The device and method enable a broad range of data transmission rates and are full compatible with communicating units operating according to previous modes in which a first data transmission rule defines the acceptable range of values of element identification parts. In the method, a second data transmission rule is implemented in at least one of the communicating units to extend the acceptable range of values of element identifications. The range of values is extended so that a second standard portion of the element identification part marks the information element as a second information element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of International Patent ApplicationNo. PCT/DE2003/004218 filed Dec. 19, 2003, which claims priority toGerman Patent Application No. 103 00 366.5 filed Jan. 6, 2003, both ofwhich applications are hereby incorporated by reference in theirentireties herein.

FIELD OF THE INVENTION

The invention relates to methods for data transmission in wireless localarea networks. The invention, in particular, relates to methods forincreasing data transmission rates between communication units which maybe operating in diverse modes.

BACKGROUND OF THE INVENTION

Data transfer in wireless local area networks between a first and secondcommunicant may involve a first standardized data transmission rule orformat and transmission and/or reception on electromagnetic signal pathsof information elements with variant element formats. The informationelements in this case may include an element identification part, alength statement part and an information part. The elementidentification part has a permissible value range from which a firststandardized value of the element identification part identifies theinformation element as a first information element. The information partof the first information element contains parameters which relate to thedata transmission of the communicant in accordance with a first datatransmission rule as the transmitter. A receiving communicant stores theparameters which relate to the transmitting communicant in order to setthe data transmission in the reply to the transmitting communicant. Onidentification of a value of the element identification part outside thepermissible value range, each of the communicants, as the receiverdetermines the length of the information part from the length statementpart, and jumps over the information part corresponding to thedetermined length.

A communication device for data transmission in wireless networks may beconnected as the first communicant in such networks to a secondcommunicant via electromagnetic signal paths. The communication devicehas at least one transmitting unit. In this case, a first datatransmission rule (which defines first information elements comprisingan element identification part, a length statement part and aninformation part) is implemented in the communication device and definesa permissible value range for the element identification part.

The importance of wireless networks has increased continuously in recentyears. Their usage capabilities appear to be unlimited. The simplestoption is to use two or more hosts (communicants) with wireless networkcards in a so-called ad-hoc network.

If it is intended to connect the wireless network (WLAN) to a wire-basedlocal area network (LAN), an access point (AP) is required. A networkstructure such as this is also referred to as a distribution system(DS).

An access point (first communicant) forms a radio cell with at least oneindividual station (second communicant).

The increase in coverage is achieved by additional cells with two ormore access points. Each access point acts like a traditional networkbridge.

One problem which has prevented wider use of WLANs was the inadequatestandardization for a long time. This situation has now changed with anincreasing tempo since the Institution of Electrical and ElectronicsEngineering (IEEE) has adopted WLAN Standards in recent years. See e.g.,Publication XP002206839, IEEE standard for information technologytelecommunication and information exchange between systems—local andmetropolitan area networks—specific requirement, Part II: wireless LANmedium access control (MAC) and physical layer (PHY) specification,(ISO/IEC 8802-11, ANSI/IEEE Std. 802.11-1999), Aug. 20, 1999.

One such disadvantage was also that wireless networks did not allow suchhigh data transmission rates as wire-based networks.

This was because the bandwidths provided by the regulators are limitedand wireless networks have to introduce additional security mechanismsand expanded information in the data packets in order to make itpossible to take account of the characteristic of a radio link.

Since radio links are more susceptible to interference than cables,additional correction mechanisms have been introduced in the MAC layerin Standard 802.11.

In the event of data transmission errors, these correction mechanismsensure that the data packets are sent again, without any involvement ofhigher protocol layers in this process. This may now possibly lead tolengthened data transmission times in comparison to the quite error-freeconnection in a cable-based network.

The IEEE Committee continued the further development of the alreadyestablished WLAN Standard 802.11 by supplementing 802.11a for 5 Ghz and802.11b for 2.4 Ghz.

At the moment, a further increase in the data rate in the 2.4 Ghz bandis being worked on in the IEEE 802.11g working group. One importantfeature of the new standard is the backwards compatibility with theestablished IEEE 802.11b Standard.

The provider companies found out quite quickly that lack ofcompatibility detracts from the acceptance of their products forwireless local area network technology.

In order to allow matching to different radio channels, the 802.11Standard and its extensions 802.11a and b allow various datatransmission rates. The data rates are coded in an information elementwhich, in accordance with IEEE 802.11, allows a maximum number of 8rates and is transmitted in the beacon signal.

The IEEE 802.11g Standard provides for more than 8 data rates to beallowed. Intraoperability tests have shown that, when more than 8 datarates are notified in the conventional information element, backwardscompatibility with existing solutions is no longer guaranteed.

Consideration is now being given to improving communication devices andnetwork data transmission methods. In particular attention is directedto communication devices and data transmission methods which can achievea wide range of data transmission rates while remaining fully compatiblewith communicants operating in diverse modes including legacy modes.

SUMMARY OF THE INVENTION

Communication devices and data transmission methods are provided fornetworked communications with diverse communicants. The datatransmission methods may be implemented to achieve a wide range of datatransmission rates which are fully compatible with the various operatingmodes of the diverse communicants.

In an inventive data transmission method, at least in the case of one ofthe communicants, the first and a second data transmission rule areimplemented, and the permissible value range is expanded in such a waythat a second standardized value of the element identification partidentifies the information element as a second information element whoseinformation part contains parameters which relate to the datatransmission of the transmitting communicant in accordance with thesecond data transmission rule. This makes it possible, in addition tothe parameters for data transmission in accordance with the first datatransmission rule, to also transmit parameters for data transmission inaccordance with the second data transmission rule from the transmittingcommunicant to the receiving communicant. The second data transmissionrule therefore allows a wider range of parameters than the first, forexample. Parameters which relate to the second data transmission rulecan thus be used alternatively or in addition to the parameters whichrelate to the first data transmission rules.

The parameters which relate to the first and the second datatransmission rules are expediently clearly separated in that the firstinformation element contains only parameters which relate to the datatransmission in accordance with the first data transmission rule, andthe second information element contains only parameters which relate tothe data transmission in accordance with the second data transmissionrule.

In conjunction with the fact that information elements whose elementidentification does not correspond to the range of values are jumpedover by each communicant, the method is also backwards-compatible. Thesecond information element is advantageously jumped over on reception ofthe second information element by a communicant in which only the firstdata transmission rule is implemented. If second information elementsare sent in this case to communicants in which only the first datatransmission rule is implemented, then the element identification of thesecond information element is outside the permissible value range, andthe second information element is jumped over by the receivingcommunicant, and therefore does not cause any disturbance.

The advantage of the greater variation of parameters which relate todata transmission is achieved in particular in that when a communicantin which both data transmission rules are implemented receives thesecond information element, the parameters which relate to the first andsecond information elements are stored.

The method is advantageously carried out in such a way that the valuesin the information part of second information elements represent a setof data transmission rates which are supported by the transmittingcommunicant, in such a way that each value corresponds to one supporteddata transmission rate. A transmitting communicant thus informs thereceiving communicant about all of the data transmission rates which itcan process. The receiving communicant can then select a suitable datatransmission rate in the acknowledgement.

A refinement of the method according to the invention provides that thedifference between a data transmission rate which corresponds to onevalue and the data transmission rate which corresponds to the next valueis greater than or equal to 500 Kbit/s. A wide variation range of datatransmission rates is thus available.

In this case, it is particularly expedient for the difference to be 1Mbit/s.

A further refinement in the method provides that at most eight valuescorrespond to the data transmission rates of the first data transmissionrule, and all the other values correspond to the data transmission ratesof the second data transmission rule. This corresponds to older standardrequirements in which at most eight values were provided for thevariation of the data transmission rates.

For this purpose, it is also possible for the second information elementadditionally to contain values for data transmission rates which areequal to values for data transmission rates of the first datatransmission rule.

In this case, it is possible that when a communicant in which both datatransmission rules are implemented receives the second informationelement, only the parameters which relate to the second informationelement are stored.

The method according to the invention can also be expanded in a mannerwhich corresponds to the first and second information elements in that,in addition to the second information element, a third or furtherinformation element or elements is or are also formed, which representsor represent third or further data transmission rules.

One refinement of the method according to the invention provides thatthe data transmission rates are coded with the aid of value pairsinstead of single values. In this case, the one value of the pair codesthe data transmission rule itself and the other value codes the datarate. In this case, it is particularly expedient to make the coding ofthe data rate dependent on the data transmission rule. This allows veryflexible extension for new data transmission rules.

The object is also achieved by a communication device in which a seconddata transmission rule with an expanded value range of the elementidentification part is implemented. The transmitting unit can send twoinformation elements which are defined by a second standardized value ofthe element identification part. In this case, its information partcontains parameters which relate to the data transmission in accordancewith the second data transmission rule.

When the second communicant is unknown, this communication device makesit possible, for example, first of all to attempt to send informationelements in accordance with the second data transmission rule. In thiscase, an element identification part is provided with the standardizedvalue. At the receiver end, it is thus possible to identify atransmitter which can operate in accordance with the second datatransmission rule. If the second communicant can likewise operate usingthe second data transmission rule, it can be set to the appropriateoperating mode. If it can operate only in accordance with the first datatransmission rule, it will not be able to “understand” the standardizedvalue, since this is outside the permissible value range. This receiverwill therefore jump over the information element. A communication devicedesigned in this way does not interfere with second communicants whichare implemented as communication devices in which only the first datatransmission rule is implemented.

In one embodiment of the invention, a receiving unit which is designedfor reception of a first and of a second information element is arrangedin the communication device. The communication device according to theinvention is thus suitable not only for transmission but also forreception of information both in accordance with the first and thesecond data transmission rule.

A further embodiment of the communication device according to theinvention can be switched between first and second data transmissionrules as a function of the reception of information elements duringtransmission. The communication device is thus both backwards andforwards compatible. Specifically, if information is received inaccordance with the first data transmission rule, the communicationdevice can switch to operate with the first data transmission rule, andboth communicants then continue their communication on the basis of thefirst data transmission rule.

If the communication device receives information with the second datatransmission rule—for example by means of an identically designedcommunication device as the communicant at the other end, it will switchto operate in accordance with the second data transmission rule.

The communication device according to the invention is advantageouslyprovided with a memory which is designed to store parameters of receivedsecond information elements. By way of example, the communication canthus be started straight away in accordance with the second datatransmission rule at a later time, when this is stored, since the seconddata transmission rule was already relevant in a previous communication,and it can be assumed that the same communicant is still located in thevicinity. This therefore makes it possible initially to avoid the timefor matching to the data transmission rule.

One development provides for a memory to be arranged, which is designedto store parameters of the received first and second informationelements. In consequence, the same method as that described above canalso be used for the first data transmission rule.

It is particularly advantageous to develop the communication device insuch a way that a third or further data transmission rule or rules is orare implemented in the same way as the second data transmission rule.This also makes it possible to widen the backwards and forwardscompatibility for other data transmission rules.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention, its nature, and various advantageswill be more apparent from the following detailed description and theaccompanying drawings, wherein like reference characters represent likeelements throughout, and in which:

FIG. 1 is a schematic representation of an exemplary an informationelement design, in accordance with the principles of the presentinvention; and

FIG. 2 is a block diagram of the data transmission processes in awireless local area network, in accordance with the principles of thepresent invention.

The following list is an index of the reference characters or numeralsthat are used in FIGS. 1 and 2 to identify drawing elements.

LIST OF REFERENCE SYMBOLS

-   1. ERP Access point-   2. Station-   3. Data transmission test procedure-   4. Test requirement-   5. Test response-   6. Radio beacon signal for the ERP access point-   7. First authentication-   8. Second authentication-   9. Request for association-   10. Association response-   11. State of the successful association of the ERP access point-   12. State of the successful association of the ERP station-   13. Radio beacon signal transmission process-   14. Element identification part-   15. Length statement part-   16. Information part-   17. Information elements-   18. Association process-   19. Extended supported rates ID-   20. Extended supported rates field

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Communication devices and data transmission methods are provided forachieving high data transmission rates between heterogeneouscommunicants. An exemplary implementation of the invention is describedherein with reference to a “critical case” according to the prior art ofsuccessful data transmission between an ERP access point 1 and a station2 which is designed according to the prior art.

FIG. 1 shows a basic configuration of an information element 17. Theinformation element 17 comprises the element identification part 14, thelength statement part 15, and the information part 16. The informationelement 17 therefore contains all the important data in order toimplement the data transmission rule.

FIG. 2 shows three possible options for data rate communication for thedata transmission processes:

data transmission test procedure 3

radio beacon signal transmission process 13

association process 18

An access point which operates on the basis of the second datatransmission rule is referred to in the following text as an ERP accesspoint (Extended Rate Phy access point 1).

The data rate communication takes place between the ERP access point 1and a station 2, which has the known data transmission rules accordingto the prior art.

In the data transmission test procedure 3, the station 2 uses a testrequest 4 which contains the element identification part 14 to requestthe ERP access point 1 for identification.

Since the ERP access point 1 has the data transmission rules accordingto the invention, it can respond with the test response 5 with thecorrect element identification part 14 which can be understood by thestation 2, and can signal its information element 17.

In the radio beacon signal transmission process 13, the ERP access point1 transmits its radio beacon signal 6 at regular intervals, whichsignals to all of the stations in the radio cell the information element17 according to the first data transmission rule and according to thesecond data transmission rule. The station 2 stores the informationelement according to the first data transmission rule, and ignores theinformation element according to the second data transmission rule.

During the association process 18, the station 2 initiates a firstauthentication 7, which requests the ERP access point 1 to respond witha second authentication 8. Since the ERP access point 1 has the datatransmission rules according to the invention, the communication fromthe station 2 can be continued with the request for association 9, andthe ERP access point 1 responds with the association response 10. Bothstations then assume the respective state of the successful association11; 12.

It will be understood that the foregoing is only illustrative of theprinciples of the invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention.

1.-18. (canceled)
 19. A method for data transmission in wireless localarea networks in which data transmission is implemented between a firstand a second communicant, and in which a first standardized datatransmission rule is implemented requiring transmission and/or receptionof information elements with variant element formats on electromagneticsignal paths, with the information elements comprising an elementidentification part, a length statement part and an information part,and the element identification part having a permissible value range inwhich a first standardized value of the element identification partidentifies the information element as a first information element whoseinformation part contains parameters which relate to the datatransmission of the communicant in accordance with a first datatransmission rule as the transmitter, a receiving communicant storingthe parameters for the transmitting communicant in order to set the datatransmission for return to the transmitting communicant, and each of thecommunicants, as the receiver determining the length of the informationpart from the length statement part on identification of a value of theelement identification part outside the permissible value range, andjumping over the information part corresponding to the determinedlength, the method comprising the step of: at least in the case of oneof the communicants, implementing in addition to the first datatransmission rule a second data transmission rule expanding thepermissible value range so that a second standardized value of theelement identification part identifies the information element as asecond information element whose information part contains parameterswhich relate to the data transmission of the transmitting communicant inaccordance with the second data transmission rule.
 20. The method asclaimed in claim 19, characterized in that the first information elementcontains only parameters which relate to the data transmission inaccordance with the first data transmission rule, and the secondinformation element contains only parameters which relate to the datatransmission in accordance with the second data transmission rule. 21.The method of claim 19 further comprising the step of jumping over thesecond information element when a communicant in which only the firstdata transmission rule is implemented receives the second informationelement.
 22. The method of claim 19 further comprising the step ofstoring the parameters which relate to the first and second informationelements when a communicant in which both data transmission rules areimplemented receives the second information element.
 23. The method ofclaim 19 wherein the values in the information part of secondinformation elements represent a set of data transmission rates whichare supported by the transmitting communicant in such a way that eachvalue corresponds to one supported data transmission rate.
 24. Themethod of claim 23 wherein the difference between a data transmissionrate which corresponds to one value and the data transmission rate whichcorresponds to the next value is greater than or equal to 500 Kbit/s.25. The method of claim 24 wherein the difference is 1 Mbit/s.
 26. Themethod of claim 23 wherein at most eight values correspond to the datatransmission rates of the first data transmission rule, and all othervalues correspond to the data transmission rates of the second datatransmission rule.
 27. The method of claim 23 wherein the secondinformation element additionally contains the values of the datatransmission rates which are equal to values for data transmission ratesof the first data transmission rule.
 28. The method of claim 27 furthercomprising the step of storing only the parameters which relate to thesecond information element when a communicant in which both datatransmission rules are implemented receives the second informationelement.
 29. The method of claim 23, further comprising the step of: inaddition to the second information element, forming a third or furtherinformation element or elements which represents or represent third orfurther data transmission rules, respectively.
 30. The method of claim23 wherein the data rates in the information element are represented byvalue pairs, wherein one value codes the data transmission rule itselfand the other value codes the data rate, and wherein the coding of thedata rate depends on the data transmission rule.
 31. A communicationdevice for data transmission in wireless networks, wherein thecommunication device can be connected as the first communicant in suchnetworks to a second communicant via electromagnetic signal paths andwhich has at least one transmitting unit, wherein a first datatransmission rule that defines a first information element comprising anelement identification part, a length statement part and an informationpart, is implemented in the communication device, wherein the first datatransmission rule defines a permissible value range for the elementidentification part, the communication device further comprising: animplementation of a second data transmission rule which expands thevalue range of the element identification part, and a transmitting unitconfigured to send second information elements which are defined by asecond standardized value of the element identification part, and whoseinformation part contains parameters which relate to the datatransmission in accordance with the second data transmission rule. 32.The communication device of claim 31, further comprising a receivingunit configured for reception of a first and of a second informationelement.
 33. The communication device of claim 31 which is switchablebetween the first and second data transmission rules in response to thereception of information elements during transmission.
 34. Thecommunication device of claim 31, further comprising a memory which isarranged to store parameters which relate to received second informationelements.
 35. The communication device of claim 31, further comprising amemory which is arranged to store parameters which relate to receivedfirst and second information elements.
 36. The communication device ofclaim 31, further comprising an implementation of at least a third datatransmission rule which is similar to the implementation of the seconddata transmission rule.